================================================================
= Fix For Altec Lansing ACS-45 Speaker System Auto Off Problem =
================================================================

     Source: http://www.cs.cmu.edu/~chuck/infopg/acs45.txt
     Author: Charles Rosenberg, chuck@cs.cmu.edu
    Version: 1.0
Last Update: 1/1/97


==========
Background
==========

I recently received the Altec Lansing ACS-45 speaker system as gift.
It has pretty good sound quality for the price.  It has one big
problem, though the auto shut off feature.  When the speaker is in
standby mode, if the system beeps, it takes a little while for the
speaker system to start up and you don't hear the beginning of the
beep.  You would think that a switch would have been included to
bypass the auto shut off feature, but no such luck.  A call to
customer support and a customer service representative told me that
the way things are is the way things are.

============
Introduction
============

I decided to take things into my own hands and open up the subwoofer /
amplifier enclosure and rewire the system so it is always on.  I did
so and it seems to work.  However, this was a quick and dirty solution
and in the process of probing the system I believe I blew out the
transistor which controls the auto on/off feature, with the result
that the speaker is always on.  So the warning with this modification
is, not only will it void your warranty, but there may be no turning
back to auto on/off once this mod is made.  The other warning is that
I have only tried this with my one speaker set.  Your speaker may be
from a different manufacturing lot and this may only result in you
having a non-functional speaker system.  So if after all that, you are
still interested in the mod, read on.

================
The Modification
================

This most difficult part of this modification is opening and closing
the subwoofer enclosure.  I would not recommend attempting this mod
unless you are comfortable with a soldering iron and you are the type
of person that can put things back together after taking them apart
and still have them work.  First make sure that the system is
unplugged from the wall and disconnected from your computer before you
start.  The back of the subwoofer is held on with 7 phillips screws.
You will need an extra long screwdriver to remove them.  Before you
separate the two halves of the case, you will need to remove the
subwoofer volume control knob, it just pulls right off.  Once you have
the case open you can slide out the PC board and make the mod.

The mod consists of a single jumper - you can make it with a soldering
iron and a blob of solder.  The two pins that need to be shorted
belong to transistor Q4.  It is the only transistor located in the
little plastic hood which houses the I/O jacks and the subwoofer
volume control.  Looking from the back of the board it looks like
this:

     ------------- <-- edge of the PC board       
        o   o      <-- pads for capacitor
     
          o A
          o B     <-- pads for transistor Q4
          o C

I've labeled the transistor pads A, B, and C.  Pads b and c need to
be connected together.  It's as simple as that.

The next thing to do is put the speaker case back together.  Be
careful not to pinch any wires.  You may have also noticed that there
was some rubber caulking inside the case to reduce vibration.  When I
put my system back together I did not install new caulking, but tried
to keep as much of the original caulking in place as I could.

==========
Final Note
==========

If, with the system constantly on, you get a slight hum, you can
resolve this by turning your computer's volume control all the way up
and the speaker's volume control down.

That's it....